Harvard and Columbia university research showing smoke from land fires in Southeast Asia led to more than 100,000 premature deaths last year “makes no sense at all,” an official at Indonesia’s Health Ministry said on Wednesday.

Indonesian government records show only 24 deaths related to forest fires in 2015, but the disaster was estimated to have left more than half a million Indonesians suffering from respiratory ailments.

Indonesia is under global pressure to put an end to slash-and-burn land clearances for palm and pulp plantations which send clouds of toxic smoke over the region each year.

The university research estimates pollution exposure from last year’s fires killed 91,600 people in Indonesia, 6,500 in Malaysia and 2,200 in Singapore in 2015 and 2016, significantly higher than government records.

“Given the severe haze in Equatorial Asia in 2015, the 100,000 premature deaths in that region are not so surprising,” said Loretta Mickley, a senior researcher at Harvard focusing on atmospheric pollution, who contributed to the research.

Health Ministry director general of disease prevention and control Mohamad Subuh told Reuters the research data was wrong.

“Data on deaths is clear. We have surveillance,” Subuh said, adding that the assumptions of mortality based on mathematical calculations were “irresponsible.”

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Every year, Indonesia faces criticism from its neighbors Singapore and Malaysia over the smog, euphemistically known as “haze”, and its failure to stop the fires from being lit.

Last year’s fires were among the worst in the region’s history, with billions of dollars worth of environmental damage, weeks of flight and school disruptions and thousands suffering from respiratory disease.